sed

读取文本文件，以行为单位处理并执行操作

参数

sed [OPTION]... {script-only-if-no-other-script} [input-file]

OPTIONS:

* -n : silent
* -i : edit file in place
* -e script
* -r,-E : Use extended regex syntax (等效于 grep 的 -E)

示例

替换配置文件内容

替换配置文件 config.yaml 里的 "interface-name: foobar" 为 "interface-name: wan" : (shell)

#!/bin/sh

WAN=wan

sed -i -e "/^interface-name:\s*/s:\:.*$:\: ${WAN}:" config.yaml

注意每次执行都会写入文件，即使当前内容已经是 interface-name: wan。如果要仅在当前配置不同时修改，加上 if 判断：

#!/bin/sh

WAN=wan

if ! grep -E "^interface-name:\s+${WAN}\s*" config.yaml
then

fi

输出正则匹配的子分组

sed -n "s/^.*foobar\s*\(\S*\).*$/\1/p"

-n     suppress printing
s      substitute
^.*    anything before foobar
foobar initial search match
\s*    any white space character (space)
\(     start capture group
\S*    capture any non-white space character (word)
\)     end capture group
.*$    anything after the capture group
\1     substitute everything with the 1st capture group
p      print it

sed in shell

字符串转义

In the shell, everything between single quotes is interpreted literally, except for single quotes themselves. You can effectively have a single quote between single quotes by writing '\'' (close single quote, one literal single quote, open single quote).

sed / grep 默认使用 basic regular expressions。这种模式下 "(){}+?|" 字符默认为 literal，前面必须加上 "\" 才表示特殊含义。使用 -E 参数让 sed / grep 使用扩展正则模式。

详细信息。